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How to take advantage of a bortle 2 on a full moon.

Sky-Watcher Star Adventurer Optolong L-eNhance Acquisition Dark Site Deep Sky
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Tomás Andonie avatar
Tomás Andonie avatar
It turns out that I will be spending 2 weeks in a sky Bortle 2 and I really want to take advantage of it, since I originally live in a sky Bortle 8. 

It will soon be a full moon, and until I leave it will only be 50% moon. Unfortunately it will be in the sky almost all night, because I don't have much time without the moon. Some nebulae that I plan to photograph are completely on the opposite side of the sky from the moon, and others quite close, within a few degrees. 

So what is the correct strategy for this case? 

Photograph nebulae without any filters and try to capture all data from the sky. Or use a narrow band L-Enhance filter and thus reduce the light reflected by the moon. 

What I don't understand is what is more beneficial. Since I know that using the L-Enhance will help me if I photograph emission nebulae (which is what I plan), but without being able to capture the surrounding interstellar dust as well. 

What are your tips in these cases? what you usually do if you have similar scenarios. Any help is welcome, and of course I have several nights to try things. 

Extra:
I use a Nikon D3300 with a Nikkor 55-300mm on a StarAdventurer 2i.
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andrea tasselli avatar
andrea tasselli avatar
Anything greater than 75% phase requires 6 hours away from the Moon and a NB filter such as yours. At 50% and 4 hours away I'd probably do it without a filter. Closer I'd use a NB filters. This is more due to the focal length than anything else (or rather FOV). At longer focal lenghts (4x-5x) I'd get closer but no closer than 4 hours away even with the filter at full Moon or close.
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Brian Puhl avatar
Brian Puhl avatar
Moon > 0 degrees,      I only shoot Ha and Sii

Moon < 0 degrees,      Broadband and Oiii.


A bortle 2 location is no longer bortle 2 under a full moon.   The moon is still light pollution.     That being said I'm not sure how much your L-enhance is going to help you under full moon, but since you have no other options...     image the other side of the sky I suppose.

The second the moon goes down though, switch over to your UV/IR filter.  You're going to get a ton more signal than you would ever get from a light polluted city sky in a fraction of the time.
I do want to note since you said "Photograph nebulae without any filters and try to capture all data from the sky."...    you need at minimum a UV/IR filter for broadband data.   You can't go without a filter.
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Brian Boyle avatar
Brian Boyle avatar
Full moon sky brightness is around 18mag/arcsec^2, about the same as Bortle 8 without moon. 

In trying to make the best of it, there is some variation in brightness over the sky from the moon, but you may find yourself quite limited to quite low altitudes (depending where you are in the world).  In the Northern hemisphere at this time the moon will be high in the sky, making your problem worse.  

If there is any haze of cloud, then the problem gets even worse.  Are you autoguiding?  That get worse too. 

Personally, I wouldn’t image when a >75% moon is up and to save your enjoyment of a B2 sky for those short periods when the moon is down or very low.   But then again, I have the luxury of living under B2 skies,  and you may just want to ‘have a go’ for the experience. 

Brian
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